Hopkins Marine Station Student Paper

Title: The interactions between rider Collisella scabra and the Lottia gigantea on which they are foundStudent Author(s): Jordan, Kathleen T.Faculty Advisor(s): Denny, MarkPages: 32Location: Final Papers Biology 175HDate: June 1988 Keywords: biological studies on gastropodsAbstract: The subpopulation of Collisella scabra found on the shells of Lottia gigantea show significant differences from the general population of C. scabra: population density is ten times less, shell/body weight ratios are higher indicating slower growth patterns possibly due to limited food availability, and density on the shell increases in areas of high growth wave action possibly due to the faster rate of algal growth in these areas. The limited foraging area on the L. gigantea shell may provide an upper limit to the number of riders it can support, as riders from crowded shells do not lower their metabolic rates. The presence of these riders on the L. gigantea removes the algal coat otherwise found on their shells. This loss of algae, the creation of the C. scabra's home scar, the added weight fo the riders, or the drag differences created by the riders cause no apparent advantage or disadvantage to the L. gigantea. While these results are in no way comprehensive, they provide a background knowledge for further studies of the species interactions.